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-rw-r--r--llvm/lib/MC/CMakeLists.txt3
-rw-r--r--llvm/lib/MC/MCParser/MasmParser.cpp10
-rw-r--r--llvm/lib/MC/MCSFrame.cpp155
3 files changed, 158 insertions, 10 deletions
diff --git a/llvm/lib/MC/CMakeLists.txt b/llvm/lib/MC/CMakeLists.txt
index 1e1d0a6..70c4577 100644
--- a/llvm/lib/MC/CMakeLists.txt
+++ b/llvm/lib/MC/CMakeLists.txt
@@ -73,9 +73,10 @@ add_llvm_component_library(LLVMMC
${LLVM_MAIN_INCLUDE_DIR}/llvm/MC
LINK_COMPONENTS
+ BinaryFormat
+ DebugInfoDWARFLowLevel
Support
TargetParser
- BinaryFormat
DEPENDS
intrinsics_gen
diff --git a/llvm/lib/MC/MCParser/MasmParser.cpp b/llvm/lib/MC/MCParser/MasmParser.cpp
index d4901d9..8a8f111 100644
--- a/llvm/lib/MC/MCParser/MasmParser.cpp
+++ b/llvm/lib/MC/MCParser/MasmParser.cpp
@@ -5844,11 +5844,11 @@ bool MasmParser::lookUpField(const StructInfo &Structure, StringRef Member,
bool MasmParser::lookUpType(StringRef Name, AsmTypeInfo &Info) const {
unsigned Size = StringSwitch<unsigned>(Name)
- .CasesLower("byte", "db", "sbyte", 1)
- .CasesLower("word", "dw", "sword", 2)
- .CasesLower("dword", "dd", "sdword", 4)
- .CasesLower("fword", "df", 6)
- .CasesLower("qword", "dq", "sqword", 8)
+ .CasesLower({"byte", "db", "sbyte"}, 1)
+ .CasesLower({"word", "dw", "sword"}, 2)
+ .CasesLower({"dword", "dd", "sdword"}, 4)
+ .CasesLower({"fword", "df"}, 6)
+ .CasesLower({"qword", "dq", "sqword"}, 8)
.CaseLower("real4", 4)
.CaseLower("real8", 8)
.CaseLower("real10", 10)
diff --git a/llvm/lib/MC/MCSFrame.cpp b/llvm/lib/MC/MCSFrame.cpp
index d6fa54c..e0a90df 100644
--- a/llvm/lib/MC/MCSFrame.cpp
+++ b/llvm/lib/MC/MCSFrame.cpp
@@ -8,6 +8,8 @@
#include "llvm/MC/MCSFrame.h"
#include "llvm/BinaryFormat/SFrame.h"
+#include "llvm/DebugInfo/DWARF/LowLevel/DWARFCFIProgram.h"
+#include "llvm/DebugInfo/DWARF/LowLevel/DWARFDataExtractorSimple.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCObjectFileInfo.h"
@@ -211,8 +213,152 @@ class SFrameEmitterImpl {
return true;
}
+ // Technically, the escape data could be anything, but it is commonly a dwarf
+ // CFI program. Even then, it could contain an arbitrarily complicated Dwarf
+ // expression. Following gnu-gas, look for certain common cases that could
+ // invalidate an FDE, emit a warning for those sequences, and don't generate
+ // an FDE in those cases. Allow any that are known safe. It is likely that
+ // more thorough test cases could refine this code, but it handles the most
+ // important ones compatibly with gas.
+ // Returns true if the CFI escape sequence is safe for sframes.
+ bool isCFIEscapeSafe(SFrameFDE &FDE, const SFrameFRE &FRE,
+ const MCCFIInstruction &CFI) {
+ const MCAsmInfo *AI = Streamer.getContext().getAsmInfo();
+ DWARFDataExtractorSimple data(CFI.getValues(), AI->isLittleEndian(),
+ AI->getCodePointerSize());
+
+ // Normally, both alignment factors are extracted from the enclosing Dwarf
+ // FDE or CIE. We don't have one here. Alignments are used for scaling
+ // factors for ops like CFA_def_cfa_offset_sf. But this particular function
+ // is only interested in registers.
+ dwarf::CFIProgram P(/*CodeAlignmentFactor=*/1,
+ /*DataAlignmentFactor=*/1,
+ Streamer.getContext().getTargetTriple().getArch());
+ uint64_t Offset = 0;
+ if (P.parse(data, &Offset, CFI.getValues().size())) {
+ // Not a parsable dwarf expression. Assume the worst.
+ Streamer.getContext().reportWarning(
+ CFI.getLoc(),
+ "skipping SFrame FDE; .cfi_escape with unknown effects");
+ return false;
+ }
+
+ // This loop deals with dwarf::CFIProgram::Instructions. Everywhere else
+ // this file deals with MCCFIInstructions.
+ for (const dwarf::CFIProgram::Instruction &I : P) {
+ switch (I.Opcode) {
+ case dwarf::DW_CFA_nop:
+ break;
+ case dwarf::DW_CFA_val_offset: {
+ // First argument is a register. Anything that touches CFA, FP, or RA is
+ // a problem, but allow others through. As an even more special case,
+ // allow SP + 0.
+ auto Reg = I.getOperandAsUnsigned(P, 0);
+ // The parser should have failed in this case.
+ assert(Reg && "DW_CFA_val_offset with no register.");
+ bool SPOk = true;
+ if (*Reg == SPReg) {
+ auto Opnd = I.getOperandAsSigned(P, 1);
+ if (!Opnd || *Opnd != 0)
+ SPOk = false;
+ }
+ if (!SPOk || *Reg == RAReg || *Reg == FPReg) {
+ StringRef RN = *Reg == SPReg
+ ? "SP reg "
+ : (*Reg == FPReg ? "FP reg " : "RA reg ");
+ Streamer.getContext().reportWarning(
+ CFI.getLoc(),
+ Twine(
+ "skipping SFrame FDE; .cfi_escape DW_CFA_val_offset with ") +
+ RN + Twine(*Reg));
+ return false;
+ }
+ } break;
+ case dwarf::DW_CFA_expression: {
+ // First argument is a register. Anything that touches CFA, FP, or RA is
+ // a problem, but allow others through.
+ auto Reg = I.getOperandAsUnsigned(P, 0);
+ if (!Reg) {
+ Streamer.getContext().reportWarning(
+ CFI.getLoc(),
+ "skipping SFrame FDE; .cfi_escape with unknown effects");
+ return false;
+ }
+ if (*Reg == SPReg || *Reg == RAReg || *Reg == FPReg) {
+ StringRef RN = *Reg == SPReg
+ ? "SP reg "
+ : (*Reg == FPReg ? "FP reg " : "RA reg ");
+ Streamer.getContext().reportWarning(
+ CFI.getLoc(),
+ Twine(
+ "skipping SFrame FDE; .cfi_escape DW_CFA_expression with ") +
+ RN + Twine(*Reg));
+ return false;
+ }
+ } break;
+ case dwarf::DW_CFA_GNU_args_size: {
+ auto Size = I.getOperandAsSigned(P, 0);
+ // Zero size doesn't affect the cfa.
+ if (Size && *Size == 0)
+ break;
+ if (FRE.Info.getBaseRegister() != BaseReg::FP) {
+ Streamer.getContext().reportWarning(
+ CFI.getLoc(),
+ Twine("skipping SFrame FDE; .cfi_escape DW_CFA_GNU_args_size "
+ "with non frame-pointer CFA"));
+ return false;
+ }
+ } break;
+ // Cases that gas doesn't specially handle. TODO: Some of these could be
+ // analyzed and handled instead of just punting. But these are uncommon,
+ // or should be written as normal cfi directives. Some will need fixes to
+ // the scaling factor.
+ case dwarf::DW_CFA_advance_loc:
+ case dwarf::DW_CFA_offset:
+ case dwarf::DW_CFA_restore:
+ case dwarf::DW_CFA_set_loc:
+ case dwarf::DW_CFA_advance_loc1:
+ case dwarf::DW_CFA_advance_loc2:
+ case dwarf::DW_CFA_advance_loc4:
+ case dwarf::DW_CFA_offset_extended:
+ case dwarf::DW_CFA_restore_extended:
+ case dwarf::DW_CFA_undefined:
+ case dwarf::DW_CFA_same_value:
+ case dwarf::DW_CFA_register:
+ case dwarf::DW_CFA_remember_state:
+ case dwarf::DW_CFA_restore_state:
+ case dwarf::DW_CFA_def_cfa:
+ case dwarf::DW_CFA_def_cfa_register:
+ case dwarf::DW_CFA_def_cfa_offset:
+ case dwarf::DW_CFA_def_cfa_expression:
+ case dwarf::DW_CFA_offset_extended_sf:
+ case dwarf::DW_CFA_def_cfa_sf:
+ case dwarf::DW_CFA_def_cfa_offset_sf:
+ case dwarf::DW_CFA_val_offset_sf:
+ case dwarf::DW_CFA_val_expression:
+ case dwarf::DW_CFA_MIPS_advance_loc8:
+ case dwarf::DW_CFA_AARCH64_negate_ra_state_with_pc:
+ case dwarf::DW_CFA_AARCH64_negate_ra_state:
+ case dwarf::DW_CFA_LLVM_def_aspace_cfa:
+ case dwarf::DW_CFA_LLVM_def_aspace_cfa_sf:
+ Streamer.getContext().reportWarning(
+ CFI.getLoc(), "skipping SFrame FDE; .cfi_escape "
+ "CFA expression with unknown side effects");
+ return false;
+ default:
+ // Dwarf expression was only partially valid, and user could have
+ // written anything.
+ Streamer.getContext().reportWarning(
+ CFI.getLoc(),
+ "skipping SFrame FDE; .cfi_escape with unknown effects");
+ return false;
+ }
+ }
+ return true;
+ }
+
// Add the effects of CFI to the current FDE, creating a new FRE when
- // necessary.
+ // necessary. Return true if the CFI is representable in the sframe format.
bool handleCFI(SFrameFDE &FDE, SFrameFRE &FRE, const MCCFIInstruction &CFI) {
switch (CFI.getOperation()) {
case MCCFIInstruction::OpDefCfaRegister:
@@ -265,10 +411,11 @@ class SFrameEmitterImpl {
FRE = FDE.SaveState.pop_back_val();
return true;
case MCCFIInstruction::OpEscape:
- // TODO: Implement. Will use FDE.
- return true;
+ // This is a string of bytes that contains an arbitrary dwarf-expression
+ // that may or may not affect unwind info.
+ return isCFIEscapeSafe(FDE, FRE, CFI);
default:
- // Instructions that don't affect the CFA, RA, and SP can be safely
+ // Instructions that don't affect the CFA, RA, and FP can be safely
// ignored.
return true;
}
generated by cgit v1.1 at 2025-10-25 22:04:13 +0000